(i) Field of the Invention
The present invention relates to a method for preparing 3-ethylbenzophenone represented by the formula (I) which is important as a material for the synthesis of medicines, Ketoprofen (trade name): ##STR2##
(ii) Description of the Prior Art
As a method for preparing 3-ethylbenzophenone, there is known, for example, a method in which a Friedel-Crafts alkylation is carried out by the use of benzophenone and diethyl sulfate in the presence of aluminum chloride in order to obtain the desired 3-ethylbenzophenone (Spanish Pat. No. 452500). In this Spanish patent, it is also disclosed that a ketoprofen which is a kind of medicine is synthesized from this 3-ethylbenzophenone. However, this method of Spanish patent results in the formation of various by-products, though high-purity raw materials are employed therein. Consequently, in the Spanish patent, the purification of the desired product is difficult and its yield is low.